1. Field of the Invention
The present invention relates to an optical on and from which data is recorded and reproduced, and to an optical apparatus that uses the optical as a recording medium.
2. Description of the Related Art
Optical discs, generally known as xe2x80x9ccompact discs,xe2x80x9d are used in increasing numbers. Each optical comprises a resin substrate that is about 120 mm in diameter and about 1.2 mm in thickness. The substrate has a signal-recording surface having recording areas, in which digital data is recorded. The digital data has been subjected to error correction performed by using CIRCs (Cross Interleave Reed-Solomon Codes) or to EFM (Eight-to-Fourteen Modulation).
Compact discs (hereinafter referred to as xe2x80x9cCDsxe2x80x9d) were developed first as media for recording digital audio data. As they are commonly used in increasing numbers, they are now put to various uses.
Particularly in recent years, optical discs for reproducing only called xe2x80x9cCD-ROM (Read-Only Memory) have come into common use. This is because personal computers are now used in many households as information-processing apparatuses, and CD-ROMs are used as media to record the information processed by the personal computers.
Optical discs of other types, which can record data recorded on the reproduction-only optical discs such as CD-ROMs, have been developed and come into practical use. They are recordable optical discs called xe2x80x9cCD-R (Recordable)xe2x80x9d and rewritable optical discs known as xe2x80x9cCD-RWs.xe2x80x9d
Hereinafter, the CDs (Compacts) and the other optical discs derived from the CDs shall be generally referred to as xe2x80x9cCD-families.xe2x80x9d The recording areas of each CD-family, in which data may be recorded, have a physical address each. The physical address indicates the position of the recording area. To record data in a target recording area or reproduce data therefrom, the optical head of an optical apparatus makes an access to the target recording area in accordance with the physical address of the recording area.
The access of the optical head to the target recording area is controlled by the controller incorporated in the optical apparatus. The controller calculates the distance the optical head should move to reach the target area, from the physical address of the target area. The optical head is moved in the radial direction of the CD-family for the distance the controller has calculated. The optical head can therefore make an access to the target recording area of the CD-family.
The physical address of each recording area of any CD-family is written in the Q channel of the subcode that is contained in the data recorded on the recording area. In a CD-ROM developed for the purpose of recording computer data and the like, the physical address of each recording area is written not only in the Q channel of the subcode, but also in the starting part of user data, called xe2x80x9cblock header.xe2x80x9d In a CD-R or a CD-RW on which data can be recorded, the physical address of each recording area is written not only in the Q channel and block header of the subcode, but also in the wobbling groove that is made in the surface of the substrate.
In the CD-familys of the existing format, the physical address of each recording area is written in the MSF (Minutes: Seconds: Frames). This is because CDs were developed in order to record digital audio data, which is best handled if the physical addresses of the recording areas are time-axis data.
Thus, in a CD-family of the existing format, the MSF-format physical address is set at the minimum value of xe2x80x9c00 (minute): 00 (second): 00 (frame),xe2x80x9d for the starting position of the program area which is the innermost user-data area of the disc. The MSF-format physical address of the recording area next to the program area has an MSF-format physical address set at a greater value. The farther each recording area is located from the starting position of the program area, the greater the value its MSF-format physical address has.
A TOC (Table of Contents) is written in the read-in area and the like that are provided on the center part of each CD-family, for recording data other than the user data. Of these areas provided on the center part of the disc, the innermost one that is immediately adjacent to the above-mentioned program area has the value of xe2x80x9c99 (minutes): 59 (seconds): 74 (frames),xe2x80x9d which is the maximal in the MSF format. In the center part of the disc, the farther each area is located from the center of the disc, the greater the value its MSF-format physical address has. The value of a physical address changes from the maximum to the minimum, and vice versa, at the starting position of the program area.
Since physical addresses are set as described above, the physical address of the starting part of user data is represented by time-axis data of xe2x80x9c00 (minute): 00 (second): 00 (frame).xe2x80x9d This scheme of setting of physical addresses is very useful in the case where the user data is, for example, audio data.
If physical addresses are set as indicated above, however, the value of a physical address changes from the maximum to the minimum, and vice versa, at the starting position of the program area. To move the optical head from any program area to the center part of the disc, or vice versa, to reach any target position on the disc, complex calculation is required to find the distance the optical head must move, from the physical addresses of recording areas. Consequently, it would take much time to calculate the distance.
A double-density CD format is now studied, which is compatible with the exiting CD format and which can increase the storage capacity of a CD twice as much as that of the existing CD format. It is proposed that, in the double-density CD format, a higher unit of time, i.e., hour, be added to the MSF-format physical address, to provide an HMSF (Hour; Minutes: Seconds: Frames) format. If the physical addresses are so set in the double-density CD format, however, more complex calculation is required to find the distance the optical head should move from any program area to the center part of the disc, or vice versa, to reach any target position on the disc. This may greatly increase the time the optical head needs to make an access to the target recording area.
The present invention has been made in view of the foregoing. An object of the invention is to provide an optical disc with which it is easy to calculate the distance an optical head should move to any target recording area, thus achieving a fast access to the target recording area. Another object of the invention is to provide an optical disc apparatus that uses such an optical disc as a recording medium.
According to the first aspect of the present invention, there is provided an optical disc that has a recording surface including a program area for recording user data and auxiliary recording areas for recording data other than the user data; and a spiral track provided in the recording surface, wobbling at a predetermined frequency and defining wobble information. The wobble information represents physical addresses of the recording areas, the value of which gradually increases from the innermost part of the disc toward the outermost part of the disc, over the entire radius of the recording area.
According to the second aspect of the invention, there is provided an optical disc that has a recording surface including a data area for recording program data and a read-in area provided inside the data area. In the optical disc, the physical address of each recording area provided in the recording surface is recorded in both the first format that is time-axis data and the second format that is binary data. The value of the physical address gradually increases from the innermost part of the disc toward the outermost part of the disc, over the entire radius of the recording area, while the first format and the second format remains in one-to-one correspondence.
According to the third aspect of the invention, there is provided an optical disc apparatus that comprises: a motor for rotating an optical disc; an optical head for applying a focussed beam to the optical disc rotated by the motor and detecting a beam reflected from the optical disc; an access mechanism for causing the optical head to make an access to any desired position on the optical disc; and a controller for detecting physical addresses of recording areas provided on the optical disc and for controlling the access mechanism in accordance with the physical addresses. When the optical disc is one that has recording areas, each having a physical address recorded in both the first format that is time-axis data and the second format that is binary data, the controller determines that the physical address value gradually increases from the innermost part toward the outermost part of this disc, while the first format and the second format remains in one-to-one correspondence, for all recording areas including a program area for recording user data and auxiliary recording areas for recording data other than the user data. The controller then controls the access mechanism in accordance with the physical address thus increasing.
According to the fourth aspect of this invention, there is provided an optical disc apparatus that comprises: a motor for rotating an optical disc having a recording surface including a program area for recording user data and auxiliary recording areas for recording data other than the user data, and a spiral track provided in the recording surface, wobbling at a predetermined frequency and defining wobble information; an optical head for applying a focussed beam to the optical disc rotated by the motor and detecting a beam reflected from the optical disc; and a controller for controlling the optical head, thereby to record user data and subcodes in the recording surface including the program area and auxiliary recording areas such that address data contained in each subcode gradually increases from the inner most part toward the outermost part of this disc, over the entire radius of the disc.
According to the fifth aspect of the invention, there is provided an optical disc apparatus that comprises: a motor for rotating an optical disc; an optical head for applying a focused beam to the optical disc rotated by the motor and detecting a beam reflected from the optical disc; an access mechanism for causing the optical head to make an access to any desired position on the optical disc; and a controller for determining whether the optical disc rotated by the motor is a first optical disc or a second optical disc, and controlling the access mechanism such that physical addresses are recorded on the optical disc along with the user data, in a first recording method when the optical disc rotated by the motor is found to be the first disc, and in a second recording method when the optical disc rotated by the motor is found to be the second optical disc having a lower recording density than the first optical disc.
In an optical disc according to the present invention, the physical address value gradually increases from the innermost part of the disc toward the outermost part of the disc, over the entire radius of the disc. Therefore, the distance the optical head must move to reach a target recording area can be calculated by using the same formula, no matter where on the disc the optical is located at present. Namely, the distance can be calculated easily, whereby the optical head fast makes an access to the target recording area.
An optical disc apparatus according to the invention comprises a disc-rotating means, an access means, and an optical head. To the disc rotating means there is connected to an optical disc on which the physical addresses of recording areas are recorded in both the first format (i.e., time-axis data format) and the second format (binary data format). The physical address value gradually increases from the innermost part of the disc toward the outermost part of the disc, over the entire radius of the disc. The access means is controlled in accordance with the physical addresses. Since the physical addresses are recorded in both the first format and the second format, it is easy to calculate the distance the optical head must move to reach a target recording area. Hence, the optical head fast makes an access to the target recording area.